Training for the “Afterburn”.
What is E.P.O.C? After we warm up and begin a greater intensity of exercise, our body must choose which energy system to use based on our intensity level. During this time, it starts taking in more oxygen until we get our “second wind” and our oxygen demands are eventually met. This is most noticeable for runners, it’s that uncomfortable feeling you get before you arrive to that “second wind” state. The “second wind” state for most runners, is more comfortable as the body has adjusted to the activity and is in drive mode.
Alternatively, HIIT – High Intensity Interval Training, does not allow your body to enter the “second wind” state, as your heart rate is taken up and then dropped several times throughout the workout. Once exercise has stopped, the body continues to take in more extra oxygen at a greater consumption than it would with a lower intensity training session. Put simply, the greater the intensity, the more oxygen and calories your body requires recovering from the exercise.
This excess oxygen, what we refer to as EPOC or Excess Post-Exercise Oxygen Consumption, is used for recovery processes that bring the body back to its normal relaxed state. (Eg: returning core body temperature and heart rate to normal, repair of muscle tissue etc)
The intensity and duration of the HIIT workout determines how long it takes for our body to return to normal, thus affecting the “after burn”. When we don’t exercise hard, we don’t get a noticeable after burn. After high-intensity exercise, however, the after burn can last hours or even days. It is not unusual for a person’s calorie count continued to climb as much as 300 kcals in the first hour after a 500 kcal effort. That intense after burn will not stay that high for more than a couple of hours at most. However, even 24-48 hours after the workout, you might still see an extra 25 kcals being burned in an hour.
Simply put, the more intense your workouts, the more energy you will expend to assist with the recovery after the workout. Thus, the longer the recovery period, the longer your body will continue to burn calories.
By incorporating some high-intensity workouts (85% – 90% of HRM) in your weekly routine, you will not only burn more calories during the workout, but you will burn additional calories during the recovery period.